Knowing the weight of an aircraft and its center of gravity are of critical importance to a pilot. A plane's weight impacts flight performance, fuel usage, cargo capacity, and even landing fees at an airport. The Federal Aviation Administration (FAA) also regulates the allowed weight of an aircraft with takeoff requirements and load limits.
In the past, weight and center of gravity determination was a long and laborious procedure. It typically required jacking the aircraft at several points through load cells or towing the aircraft onto properly arranged weighing scales. For example, U.S. Pat. No. 4,502,555 to Gower discloses a portable weighing system for aircraft which includes a plurality of load cells which are connected to a central computing and display unit. The computer within the central unit compensates by its programming for nonlinearities in the response of the load cells. The output display can include aircraft gross weight and center of gravity as a percentage of mean aerodynamic chord (MAC).
U.S. Pat. No. 3,797,302 to Laimins discloses an on-board aircraft weight transducer with mechanical offset adjustment. This externally mounted strain-gage transducer senses an aircraft's weight by measuring load-induced deformations of a support such as an axle, truck beam, or the like. The device comprises an elongated form with end lugs designed for bolting to cooperating horizontally-spaced lugs integral within the support. The transducer end lugs each are provided with an adjustably-deformable hole-and-slot type symmetrical flexural connection by which the transducer ends may be raised or lowered in the vertical direction.
A need exists for a method and apparatus for weighing aircraft which does not rely on gages which measure structural deformation. A need exists for a device capable of easy installation which measures the hydraulic pressure in the landing gear of the aircraft and which can correlate this measurement to an aircraft weight and center of gravity location. This device should further incorporate a display unit for the operator or the pilot which will warn him of underload and overload conditions, or a situation where the center of gravity of the plane is located such that flying would be unsafe.